SOAP architecture and message format

SOAP is a protocol for the exchange of information in a distributed environment. SOAP messages are encoded as XML documents and can be exchanged using various underlying protocols.

Formerly an acronym for Simple Object Access Protocol, SOAP is developed by the World Wide Web Consortium (W3C), and is defined in the following documents issued by W3C. Consult these documents for complete, and authoritative, information about SOAP.

The SOAP specifications describe a distributed processing model in which a SOAP message is passed between SOAP nodes. The message originates at a SOAP sender and is sent to a SOAP receiver. Between the sender and the receiver, the message might be processed by one or more SOAP intermediaries.

A SOAP message is a one-way transmission between SOAP nodes, from a SOAP sender to a SOAP receiver, but messages can be combined to construct more complex interactions, such as request and response, and peer-to-peer conversations.

The specification also includes this information:
  • A set of encoding rules for expressing instances of application-defined data types.
  • A convention for representing remote procedure calls and responses.